The proposed research continues the study of the response of monkey infants to mother loss, in order to illuminate processes of adaptation to a common crisis as well as the role of object loss in depression. From these two perspectives we have studied 1) factors which influence the infant's reaction and 2) the reaction itself. We found that the reaction consists of three stages which we have viewed as successive efforts at adaptation through changes in organismic state. These states have affective aspects which are akin to to anxiety during agitated searching, the 1st stage, and to depression during conservation-withdrawal, the 2nd stage. The depressive withdrawal is sometimes so extreme that infants die. We found that separated pigtail infants show a much more profound reaction than bonnets, apparently because: pigtails miss their mothers more, have less adequate coping ability at this age, and get less substitute mothering than bonnets, and in fact receive more aggression. The proposed project will study further two of the factors which influence the infant's reaction: the availability and adequacy of the infant's coping behavior, and the availability and adequacy of substitute mothering. 1) We shall study the issue of coping by teaching pigtail infants behavioral techniques for dealing with the stress of an inaccessible (caged) mother. This will enable us to explore the relationship between coping and helplessness, as well as the role of helplessness in states of depression. 2) We shall study the issue of substitute mothering by using mixed species groups. We expect to increase the availability and adequacy of substitute mothering for pigtail infants by providing familiar bonnet mothers, while we expect to decrease the availbility and adequacy for bonnet infants by including pigtail mothers in the group. Under these altered circumstances, separated pigtail infants may show a less severe reaction, and separated bonnet infants a more severe reaction, than we have seen before.